Processes to prepare aviation fuel are performed in a refinery environment wherein from a crude mineral oil source an aviation fuel and an automotive gas oil are prepared. Typically the crude mineral oil is separated by means of distillation into a distillate kerosene fraction boiling in the aviation fuel range and a distillate gas oil fraction boiling in the automotive gas oil range. If required, these fractions are subjected to hydroprocessing to reduce sulphur and nitrogen levels. In more complex refineries, higher boiling fractions and residual fractions of the crude oil are subjected to conversion processes involving optionally hydrogen, wherein part of the high boiling compounds are converted, i.e. cracked, to lower boiling compounds boiling in the respective aviation fuel and automotive gas oil ranges. In order to achieve a finished fuel product, blends of the aforementioned sources of kerosene and gas oil fractions are made. A refinery operation as above typically involves a complex scheduling operation whereby, depending on the crude oil feed and the desired oil products, an optimal processing and blending scheme results. When preparing aviation fuel products and gas oil in a summer period from a crude oil source, scheduling problems have to be solved. In a summer period there is a higher need for aviation fuel due to an increase in the holiday travel as compared to the winter period.